Microstructure and tribological performances of M50 bearing steel processed by ultrasonic surface rolling

To prolong service life of M50 steel for the main shaft bearing, ultrasonic surface rolling process (USRP) was utilized to improve surface performances. The effects of USRP on surface integrity and tribological behavior were investigated. The results show the effect of USRP parameters on surface performances follows the order: feed rate > load > rolling times. During the USRP treatment, plastic deformation layer with 24 mu m thickness is formed, and fine grain strengthening increases the microhardness (15.56%) and residual stress (79.61%) and decreases the surface roughness (-68.09%), respectively. Friction coefficient and wear rate of USRP sample are lower than those of untreated sample, because USRP helps form a smooth tribolayer and changes the main wear mechanism to slight adhesive wear.

Automated summary

This study investigates the use of ultrasonic surface rolling process (USRP) to improve the service life of M50 steel main shaft bearing. The results show that USRP treatment forms a plastic deformation layer, enhances microhardness and residual stress, and improves surface roughness. Compared to untreated samples, USRP samples exhibit lower friction coefficient and wear rate, with a shift in the main wear mechanism towards slight adhesive wear.